For this purpose, the delivery device is conventionally a syringe with a hypodermic needle which punctures the perforable closure or plug of the receptacle, for example, an infusion container. After puncture, by pressing the syringe, the medium is injected into the receptacle. In this process the preparatory working step of filling the syringe is necessary, in which the desired amount of the medium from a storage container is transferred into the syringe or the syringe is filled from a conventional vial which contains the measured dose of the pertinent medium. These working steps of transfer are on the one hand time-consuming, because the hypodermic needle and syringe must be unwrapped, the hypodermic needle mounted on the syringe, the vial opened or punctured and the syringe must be drawn up. On the other hand, in these measures, a major risk exists of contamination of the medium. Another problem in these delivery devices is the danger of injury to which the user is exposed during handling and which may be caused by the tip of the hypodermic needle. In this respect, a known delivery device, disclosed in U.S. Pat. No. 4,735,618, includes a safety device which has a safety body covering the end of the hypodermic needle and which can be moved from the effective protective state into the inactive state intended for delivery of the medium from the hypodermic needle. For this purpose, the safety body can be pushed along the hypodermic needle between an advanced protective position on the end of the hypodermic needle and the retracted state of use.
The disadvantage in this known device is that there are no provisions against unintentional movement into the position of use, in which the end of the hypodermic needle projects exposed. The known device can only be safeguarded after completed use by fitting the tip of the hypodermic needle in a receiving recess of the safety body after it has been advanced beyond the tip of the hypodermic needle after use of the device. The known device is therefore unsatisfactory from the standpoint of safety.